[vtkusers] VTK, color consistency and ICC profiles (and recent color summit)

[David Gobbi]

Hi David,

It's hard to say where color profiles would be used in VTK itself.
VTK doesn't even do gamma.  As far as I know, all ops in VTK
assume a linear scale and there isn't even a VTK filter to convert
the gamma of a photo to unity before operations like interpolation
or image addition/subtraction.

Neither does vtkImageData have a data field where things like
the gamma or color profile could be stored, and I don't see it as
a high priority to add such fields.  But I do agree that it would
be very nice if the image readers could report whatever info they
can get from the image header.

For saving images, most images saved from VTK are the result
of rendering geometrical objects via OpenGL, and I believe that
OpenGL assumes a linear intensity scale and is agnostic with
respect to color profile.  So would we assume that these
rendered images should be saved with an sRGB profile, since
most monitors should nominally be sRGB?

It would be nice if the VTK image writers had a method by which
one could set the color profile to be stored in the file header, but
I believe that handling of color profiles should be done at the
application level, and VTK should in general be agnostic.

I'm biased, though, because I deal mainly with MR and CT, and
when I use color it's qualitative.  I'd be glad to hear additional
opinions, though.

 - David


On Thu, Aug 1, 2013 at 8:58 AM, David Clunie <dclunie at dclunie.com> wrote:
> Hi all
>
> I was wondering if any VTK users and developers had any
> particularly interest in color consistency, management and
> in particular the use of ICC profiles and color calibrated
> displays.
>
> Since DICOM images can (though don't often) contain embedded
> ICC profiles, and each image may contain a different profile,
> to display these side-by-side consistently would require VTK
> to take this into account (e.g., like Photoshop does).
>
> Other requirements might include when importing non-DICOM files
> like JPEGs, if any ICC profile is embedded in the JPEG bitstream,
> it should be accounted for.
>
> Likewise, color images generated in VTK and saved, regardless
> of format, should probably be tagged with an appropriate ICC
> profile, if the format permits it.
>
> We recently had a summit on the subject, the presentations
> and the recordings of which are available at:
>
> http://www.color.org/events/medical/presentations.xalter
> http://www.color.org/events/medical/medical_summit_2013.xalter
> http://www.color.org/events/medical/medical_summit_2013_abstracts.xalter
> http://www.fda.gov/MedicalDevices/NewsEvents/WorkshopsConferences/ucm342138.htm
>
> There is also a new ICC Medical Imaging Working Group:
>
> http://www.color.org/groups/medical_imaging_wg.xalter
>
> David